The present invention relates generally to the production of tufted nonwoven fibrous web materials. More particularly, it is concerned with new and improved papermaking techniques for the production of tufted nonwoven materials and with such materials exhibiting the appearance and characteristics of high loft absorbent bath toweling and the like.
As is well known, conventional wet paper-making techniques have traditionally produced compact, closely formed sheets exhibiting the rattle and smooth surface characteristic usually associated with paper. In recent years, increased emphasis has been placed on the production of nonwoven fabrics for apparel, household and industrial uses. Such fabrics, though initially produced as dry fibrous batts processed on textile carding equipment, now include certain wet-laid webs made on paper-making machines using techniques especially developed for the production of nonwoven materials. The materials thus produced exhibit textile-like characteristics including softness, drape and hand, and have found extensive use in the field of disposable fabrics.
Many of the nonwoven fabrics produced heretofore have utilized a patterned configuration of one form or another in order to impart to the material the desirable characteristics of woven cloth. This patterned configuration has generally been achieved by subjecting a preformed web to controlled destructive forces which rearrange and reorient the fiber construction and provide a multitude of small apertures which improve the drape characteristics of the resultant nonwoven material. Typical examples of this fiber rearranging technique can be found in U.S. Pat. Nos. 2,862,251; 3,042,576 and 3,081,515.
Another technique for imparting some of the characteristics of woven fabrics to nonwoven fibrous materials is the use of a needle punch operation that forms "pegs" of fibers which increase the structural integrity of the web while improving the flexibility and hand thereof. Still other techniques involve light surface brushing to provide a raised nappy surface exhibiting improved softness, as for example in U.S. Pat. No. 3,101,520, or the use of electrostatic fiber flocking to achieve a comparable nappy surface. A further technique involves the utilization of a crepe or loop-forming operation either alone or in combination with a needle punch. The nonwoven fabrics containing the looped fibers tend to imitate the looped configuration characteristics of woven terry cloth and reportedly exhibit improved softness and high loft.
In substantially all of the foregoing processes it is necessary to first form a web and then subject it to an additional structure altering treatment to provide the desired characteristics. Additionally, in many instances the initial nonwoven web materials are not produced in accordance with the more economical web paper-making technique, thereby further adding to the cost of the finished product. Some progress has been made in producing patterned webs using a wet paper-making process and mention can be made to the dual wire technique disclosed in U.S. Pat. No. 3,322,617 and the techniques found in U.S. Pat. No. 2,940,891.
Despite these previous attempts, it was found that wet paper-making techniques had not been used successfully to produce tufted nonwoven toweling products having the loft, softness, bulk, absorbency and drape characteristics of turkish toweling. A key factor in the inability of the prior art techniques to produce such materials has been the inability of the wet process to provide high loft materials having a high concentration of absorbent relatively loose and flexible yet sturdy fibers extending outwardly from the main body of the web. However, a major step in that direction is described in our copending application Ser. No. 341,699 filed on Mar. 15, 1973 and entitled "Process of Forming Wet Laid Tufted Nonwoven Fibrous Web From a Viscous Fibrous Dispersion and Product". Described therein is a technique that provides tuft formation as the web is being formed. This is achieved using a viscous dispersing medium for the fibers and a coarse web forming wire screen. Although good tuft formation is obtained when using a screen of the type described, some entanglement of the free ends of the tufts prior to removal of the web from the screen has been experienced. Such entanglement not only adversely affects the appearance of the product but also causes difficulty in removing the web from the web forming wire.
Accordingly, it is an object of the present invention to provide an improvement in the process and product described in our aforementioned copending application and more specifically to provide an improved wet paper-making technique for producing high loft, tufty or tufted nonwoven fibrous web materials exhibiting the softness, drape, hand, feel, bulk and absorbency associated with woven looped materials such as turkish or terry toweling. Included in this object is the provision for a new and improved water-laid material exhibiting these characteristics.
Another object of the present invention is to provide a new and improved wet paper-making technique and resultant product which uniquely combines the advantageous features of the wet paper-making technology in a new and controlled manner to provide a product characterized by having on at least one surface thereof a multiplicity of fiber tufts or bundles extending outwardly from the continuous planar body portion of the product in the form of multiple strand fiber bundles exhibiting an appearance either similar to a weft of hair or a serried or consolidated fiber cluster similar to a French knot.
A further object of apertured present invention is to provide a technique of the type described utilizing a fiber suspending medium of varied viscosities and a thicker fiber collecting paper forming element that obviates entanglement between the tufts during the web forming operation. Included in this object is the provision for a technique capable of using a relatively thick aperturedd web forming element that assists in tuft formation, holds the individual tufts in spaced relationship and facilitates consolidation of the fibers within individual tufts.
Still another object of the present invention is to provide a technique and product of the type described wherein tufts are simultaneously formed on both sides of the web material during web formation.
Other objects will be in part obvious and in part pointed out in more detail hereinafter.
These and related objects are accomplished in accordance with the present invention by providing a fibrous nonwoven water-laid web material exhibiting high loft, bulk and absorbency. The web is comprised of a substantially planar web body portion of randomly arranged water dispersable fibers and a multitude of separate, spaced fiber tufts of high concentration arrayed on at least one surface thereof. The tufts are composed of a plurality of closely associated, relatively independent, substantially aligned fibers anchored within but extending from the web body portion in the form of fiber bundles exhibiting either a weft-like collapsed funnel appearance or a consolidated or serried configuration. The nonwoven web material is produced by a wet paper-making process that has been modified to include the steps of providing an aqueous fiber-dispersing medium having a controlled fluid viscosity and an apertured fiber collecting element having a plate-like structure that prevents fiber entanglement between adjacent tufts and disruptive adherence to the underside of the element. The apertured element is adapted not only to form the tufted nonwoven fibrous web with the tufts formed by bundles of closely associated individual fibers extending into the apertures but also to sufficiently isolate and control individual tufts to prevent interentanglement therebetween prior to removal from the web forming element.
A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth an illustrative embodiment and are indicative of the way in which the principles of the invention are employed.